It is very unfair that you do not give a discount to who bought Dorico versions 1 and 2. They supported you from start
Welcome to the forum Ehsan.
If I go through the Buy button for Dorico Pro 3.5, on this page: Music Notation Software - Write scores with Dorico | Steinberg
Full price: £480 (I’m in the U.K.)
Competitive crossgrade: £236
Update from Dorico Pro 3: £51
Update from Dorico 1 or Dorico 2: £136
Upgrade from Dorico Elements: £386
£136 isn’t quite as cheap as the update from Dorico Pro 3, but then again, people updating from Dorico 1 or 2 are paying to receive all the improvements in both the Dorico 3 and Dorico 3.5 development periods.